In heat exchangers between air and air which carry out heat exchanging in supplying fresh air to a room and simultaneously discharging the foul air from the room, the elements of total heat exchangers which carry out heat exchanging of latent heat (humidity) as well as sensible heat (temperature) are needed to have both heat transferability and moisture permeability, and, hence, in many cases, papers mainly composed of natural pulps are used.
Although the conventional total heat exchanging element papers have both the heat transferability and the moisture permeability, they have a problem that since porous bases are used, they also have permeability to foul gas components such as carbon dioxide, and supplied air and discharged air are mixed inside the elements in carrying out total heat exchanging to cause deterioration in efficiency of ventilation. The admixture of supplied air and discharged air is a fatal and serious defect in considering commercial products of total heat exchangers. If the supplied air and the discharged air mix with each other, it might be considered that the air inside the room and the air outside the room are not exchanged with carrying out recovery of energy, but the foul air inside the room is merely agitated with making a pretense of recovering heat. However the heat transferability may be high and however the moisture permeability may be high, if the air inside the room and the air outside the room mix with each other, ventilation cannot be performed, and, to say more bluntly, it can even be said that an electric fan can recover 100% of heat and humidity. It is a matter of course that an electric fan has no ventilating function, and the difference between a total heat exchanger which is a high-grade ventilating fan and an electric fan is simply that the former exchanges air inside a room and air outside the room without causing admixture of them while carrying out heat exchanging, in other words, it performs discharging of air from a room and supplying of air from outside. Since the value of the total heat exchangers as commercial products solely resides in the function of ventilation, the commercial value is fundamentally doubted if admixture of the supplied air and the discharged air occurs.
Various investigations have been made in an attempt to avoid the great problem of mixing of the supplied air and the discharged air. However, the total heat exchanging element papers until now have both heat transferability and moisture permeability; but are insufficient in gas barrier properties and cause considerable mixing of the supplied air and the discharged air inside the elements. This insufficient gas barrier property necessitates the use of paper (cellulose) bases in order to give moisture permeability to total heat exchanging element papers, and in order to further improve the moisture permeability, the total heat exchanging element papers must be made porous, resulting in increase of gas permeability (deterioration of gas barrier property). If the total heat exchanging element papers are not needed to have moisture permeability, not the porous bases such as papers, but plastic films which can be made thinner and are high in gas barrier property or metallic foils such as aluminum foils used in many heat exchange media will suffice for use. However, these materials are infinitely close to zero in moisture permeability, and, hence, they can perform heat exchange, but cannot perform moisture exchange, and thus cannot be used as total heat exchanging element papers.
Therefore, the object of the present invention is to provide a total heat exchanging element paper for constituting elements for total heat exchangers in which gas barrier property is enhanced with maintaining high moisture permeability and heat exchangeability and mixing of supplied air and discharged air in the element is diminished. That is, the object is to provide an excellent total heat exchanging element paper which satisfies all of the heat transferability, the moisture permeability and the gas barrier property, and further object is to provide a total heat exchanging element.